本文主要介绍通过使用CGPathRef/CGMutablePathRef哪些相关的接口可以绘制一个图形。

使用CGPathRef画矩形

    double lineWidth = 5;
    //创建矩形区域及矩形区域的路径，
    CGRect rect = CGRectMake(lineWidth, lineWidth, 100, 200);
    CGPathRef path = CGPathCreateWithRoundedRect(rect, 1, 2, nil);

    //获取图形上下文并将路径加入上下文
    CGContextRef cr = [[NSGraphicsContext currentContext] graphicsPort];
    CGContextAddPath(cr, path);
    
    //设置线条色、填充色、线条宽度
    CGContextSetRGBStrokeColor(cr, 0, 0, 255, 1); 
    CGContextSetRGBFillColor(cr, 255, 0, 0, 1);
    CGContextSetLineWidth(cr, lineWidth);
    
    //几个绘制函数
    //CGContextFillPath(cr);                        //只填充
    //CGContextDrawPath(cr, kCGPathFill);           //同上
    //CGContextStrokePath(cr);                      //只画线条
    //CGContextDrawPath(cr, kCGPathStroke);         //同上
    
    //绘制线条并对矩形进行填充
    CGContextDrawPath(cr, kCGPathFillStroke);  

    //清理
    CGPathRelease(path);

使用CGMutablePathRef画矩形

    double lineWidth = 5;
    //创建矩形区域、路径，将矩形区域加入至路径中
    CGRect rect = CGRectMake(lineWidth, lineWidth, 100, 200);
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, nil, rect);
    
    //获取图形上下文，并将path加入上下文中
    CGContextRef cr = [[NSGraphicsContext currentContext] graphicsPort];
    CGContextAddPath(cr, path);
    
    //设置线条色、填充色、线条宽度
    CGContextSetRGBStrokeColor(cr, 0, 0, 255, 1);
    CGContextSetRGBFillColor(cr, 255, 0, 0, 1);
    CGContextSetLineWidth(cr, lineWidth);
    
    //绘制
    CGContextDrawPath(cr, kCGPathFillStroke);
    
    //清理
    CGPathRelease(path);

效果如下：

image.png

平移、缩放

//获取初始状态
CGAffineTransform xf = CGAffineTransformIdentity;
//x轴平移10，y轴平移20 
xf = CGAffineTransformTranslate( xf, 10,20); 
//x轴缩放10倍，y轴缩放20倍。
xf = CGAffineTransformScale( xf, 10, 20);

由点连线绘制直角三角形(愚蠢的方法)

//创建三角形
int count = 100;
double lineWidth = 3;
//斜边
NSPoint *points1 = (NSPoint*)malloc(sizeof(NSPoint)*count);
for(int i=0; i<count; ++i){
    points1[i] = NSMakePoint(lineWidth+i, 100-i);
}
//高
NSPoint *points2 = (NSPoint*)malloc(sizeof(NSPoint)*count);
for(int i=0; i<count; ++i){
    points2[i] = NSMakePoint(lineWidth, 100-i);
}
//底边
NSPoint *points3 = (NSPoint*)malloc(sizeof(NSPoint)*count);
for(int i=0; i<count; ++i){
    points3[i] = NSMakePoint(100-i, lineWidth);
}

//创建矩形区域、路径，将矩形区域加入至路径中
CGMutablePathRef path = CGPathCreateMutable();
CGPathAddLines(path,nil, points1, count);
CGPathAddLines(path,nil, points2, count);
CGPathAddLines(path,nil, points3, count);

//获取图形上下文，并将path加入上下文中
CGContextRef cr = [[NSGraphicsContext currentContext] graphicsPort];
CGContextAddPath(cr, path);

//设置线条色、填充色、线条宽度
CGContextSetRGBStrokeColor(cr, 0, 0, 255, 1);
CGContextSetRGBFillColor(cr, 255, 0, 0, 1);
CGContextSetLineWidth(cr, lineWidth);

//绘制
CGContextDrawPath(cr, kCGPathFillStroke);

//清理
CGPathRelease(path);
free(points1);
free(points2);
free(points3);

通过坐标绘制三角形

int count = 100;
double lineWidth = 3;

//创建矩形区域、路径，将矩形区域加入至路径中
CGMutablePathRef path = CGPathCreateMutable();

//获取图形上下文，并将path加入上下文中
CGContextRef cr = [[NSGraphicsContext currentContext] graphicsPort];
CGContextAddPath(cr, path);

//高
CGContextMoveToPoint(cr,lineWidth,0);
CGContextAddLineToPoint(cr,lineWidth,count);

//斜边
CGContextMoveToPoint(cr,lineWidth,count);
CGContextAddLineToPoint(cr,count,0);

//底边
CGContextMoveToPoint(cr,count,0);
CGContextAddLineToPoint(cr,lineWidth,0);

//设置线条色、填充色、线条宽度
CGContextSetRGBStrokeColor(cr, 0, 0, 255, 1);
CGContextSetRGBFillColor(cr, 255, 0, 0, 1);
CGContextSetLineWidth(cr, lineWidth);

//绘制
CGContextDrawPath(cr, kCGPathFillStroke);

//清理
CGPathRelease(path);

效果如下：

image.png